Java中的Java.util.concurrent.CopyOnArrayList.retainAll()方法用于仅保留列表中包含在特定集合中的元素。
用法:
public boolean retainAll(Collection col)
参数:此方法接受具有收集类型的强制性参数col。这是要保留在此向量中的元素的集合。
返回类型:如果由于调用else而导致列表完全更改,则此方法返回布尔值true。
异常:如果指定的集合为NULL,则此方法引发NullPointerException。
下面的程序演示了Java中的CopyOnArrayList的retainAll()方法:
示例1:该程序涉及Integer类型的CopyOnArraylist retainAll()方法:
// Java Program to illustrate CopyOnArrayList
// retainAll() method
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
// create object of CopyOnWriteArrayList
CopyOnWriteArrayList<Integer> ArrLis1
= new CopyOnWriteArrayList<Integer>();
// Add elements
ArrLis1.add(34);
ArrLis1.add(66);
ArrLis1.add(72);
ArrLis1.add(10);
// print CopyOnWriteArrayList
System.out.println("CopyOnWriteArrayList1: "
+ ArrLis1);
// create object of CopyOnWriteArrayList
CopyOnWriteArrayList<Integer> ArrLis2
= new CopyOnWriteArrayList<Integer>();
// Add elements
ArrLis2.add(10);
ArrLis2.add(66);
ArrLis2.add(97);
// print CopyOnWriteArrayList
System.out.println("CopyOnWriteArrayList2: "
+ ArrLis2);
// Applying the function
ArrLis2.retainAll(ArrLis1);
// print CopyOnWriteArrayLists
System.out.println("After applying retainAll()"
+ " method on ArrLis2");
System.out.println("CopyOnWriteArrayList1: "
+ ArrLis1);
System.out.println("CopyOnWriteArrayList2: "
+ ArrLis2);
}
}
输出:
CopyOnWriteArrayList1: [34, 66, 72, 10] CopyOnWriteArrayList2: [10, 66, 97] After applying retainAll() method on ArrLis2 CopyOnWriteArrayList1: [34, 66, 72, 10] CopyOnWriteArrayList2: [10, 66]
示例2:该程序涉及String类型的CopyOnArraylist retainAll()方法:
// Java Program to illustrate CopyOnArrayList
// retainAll() method
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.*;
public class GFG {
public static void main(String[] args)
{
CopyOnWriteArrayList<String> ArrLis1
= new CopyOnWriteArrayList<String>();
// Add elements
ArrLis1.add("geeks");
ArrLis1.add("shaan");
ArrLis1.add("gfg");
ArrLis1.add("programming");
// print CopyOnWriteArrayList
System.out.println("CopyOnWriteArrayList1: "
+ ArrLis1);
// create object of CopyOnWriteArrayList
CopyOnWriteArrayList<String> ArrLis2
= new CopyOnWriteArrayList<String>();
// Add elements
ArrLis2.add("geeks");
ArrLis2.add("gfg");
ArrLis2.add("qwe");
// print CopyOnWriteArrayList
System.out.println("CopyOnWriteArrayList2: "
+ ArrLis2);
// Applying the function
ArrLis2.retainAll(ArrLis1);
// print CopyOnWriteArrayLists
System.out.println("After applying retainAll()"
+ " method on ArrLis2");
System.out.println("CopyOnWriteArrayList1: "
+ ArrLis1);
System.out.println("CopyOnWriteArrayList2: "
+ ArrLis2);
}
}
输出:
CopyOnWriteArrayList1: [geeks, shaan, gfg, programming] CopyOnWriteArrayList2: [geeks, gfg, qwe] After applying retainAll() method on ArrLis2 CopyOnWriteArrayList1: [geeks, shaan, gfg, programming] CopyOnWriteArrayList2: [geeks, gfg]
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注:本文由纯净天空筛选整理自kanakasrijaathukuri大神的英文原创作品 CopyOnWriteArrayList retainAll() method in Java with Examples。非经特殊声明,原始代码版权归原作者所有,本译文未经允许或授权,请勿转载或复制。